Clinical features and etiology of hepatocellular carcinoma arising in patients with membranous obstruction of the inferior vena cava: in reference to hepatitis viral infection

BACKGROUND AND AIMS

Budd-Chiari syndrome (BCS) comprises hepatic vein thrombosis and inferior vena cava (IVC) obstruction known as membranous obstruction of the IVC (MOVC). The latter is frequently complicated by hepatocellular carcinoma (HCC). The etiology of MOVC-associated HCC in relation to hepatitis viral infection is not known. In this study, we investigated the clinical features and etiology of HCC in MOVC.

METHODS

Membranous obstruction of IVC and HCC were diagnosed and studied by using imaging techniques. Sera from patients with MOVC, complicated by HCC, were examined for hepatitis viral antigens and antibodies (hepatitis B surface antigen (HBsAg), antibody to HBsAg (anti-HBs), antibody to hepatitis B core antigen (anti-HBc) and third generation antibody to hepatitis C virus (anti-HCV)) and for hepatitis viral nucleic acids (hepatitis B virus (HBV)-DNA, hepatitis C virus (HCV)-RNA, hepatitis G virus (HGV)-RNA and TT virus DNA).

RESULTS

We studied 12 patients with BCS who were seen between April 1968 and February 1999. All of them had MOVC. Hepatocellular carcinoma developed in three (25%) of them. There were no obvious differences in the clinical features and imaging findings concerning MOVC between patients with and without HCC. Hepatocellular carcinoma in these three patients showed no clear trend in clinical features and imaging findings. Of the hepatitis viral markers examined, HBsAg, anti-HBc and HBV-DNA were positive in only one of three patients with HCC and all of the viral markers were negative in the other two patients.

CONCLUSIONS

Chronic congestion in the liver, caused by an outflow block of hepatic veins and subsequent histopathologic change, must have led to HCC in two patients without any hepatitis viral markers. Patients with MOVC should be followed closely as a high-risk group for HCC.

[Acute eosinophilic pneumonia induced by cigarette smoking: positive lymphocyte stimulation test of a cigarette extract]

A 21-year-old man was admitted to our hospital with high fever, general fatigue and dyspnea. Chest radiography on admission showed diffuse bilateral infiltrate shadows with Kerley's B lines, and a CT scan showed patches of infiltrates with thickened interlobular septa in both lungs. Examination of the bronchoalveolar lavage fluid and the clinical course led to a diagnosis of acute eosinophilic pneumonia. The patient improved without steroid therapy. We suspected that the disease was related to smoking because the patient had started smoking seven days before the onset of the symptoms. Because a lymphocyte stimulation test gave a positive reaction to a cigarette extract, a challenge test was done. After this, the patient had fever and hypoxemia. These findings suggest that cigarette smoking induces acute eosinophilic pneumonia.

[Malignant islet cell tumor of the pancreas with multiple liver metastases effectively treated by transcatheter arterial embolization with degradable starch microspheres--a case report]

A 57-year-old woman underwent distal pancreatectomy for malignant islet cell tumor of the pancreas in 1991. One year later, multiple liver metastases appeared. Although three transcatheter arterial embolizations (TAE) with spongel and nine ethanol injections were performed over seven years, the tumors were growing gradually. Therefore, TAE with degradable starch microspheres (DSM) was selected. Under angiography, TAE of the left hepatic artery was done using 900 mg of DSM following injection of Farumorubicin (20 mg), Lipiodol (3 ml) and cisplatin (90 mg). The tumors in the embolized hepatic area were remarkably decreased in size, and satisfactory local control was obtained. Thereafter, TAE with DSM was carried out twice, and she is still living with outpatient treatment. Thus, it is suggested that TAE with DSM could be a promising, alternative therapeutic modality for liver metastases from malignant islet cell tumor of the pancreas.

Bradykinin stimulates IL-6 and IL-8 production by human lung fibroblasts through ERK- and p38 MAPK-dependent mechanisms

Bradykinin (BK) is a major kinin with well-documented pharmacological properties including vascular leakage and induction of a variety of cytokines. However, the intracellular signalling mechanisms by which BK induced proinflammatory cytokine production have not been fully elucidated. This study investigated the role of the extracellular signal-regulated protein kinase 1/2 (ERK 1/2) and p38 mitogen-activated protein kinase (p38 MAPK) in the BK-induced interleukin (IL)-6 and IL-8 production by human lung fibroblasts. Lung fibroblasts were stimulated with BK in the presence or in the absence of PD98059, a specific MAPK/ERK kinase-1 inhibitor, or SB203580, a specific p38 MAPK inhibitor, and IL-6 or IL-8 production and their gene expression was examined. BK-induced ERK 1/2 or p38 MAPK phosphorylation was also analysed by Western blot analysis. BK at nanomolar concentrations stimulated lung fibroblasts to produce IL-6 and IL-8 along with increased ERK 1/2 and p38 MAPK phosphorylation. BK-induced IL-6 and IL-8 synthesis was inhibited by a B2-type BK receptor antagonist. Furthermore, PD98059 or SB203580 significantly suppressed BK-induced IL-6 and IL-8 production and their gene expression. These results indicate that bradykinin-induced interleukin-6 and interleukin-8 production are at least partly mediated through the extracellular signal-related protein kinase 1/2 and p38 mitogen-activated protein kinase pathway-dependent activation in human lung fibroblasts, and suggest that bradykinin appears to be involved in the inflammatory reaction leading to acute lung injury through stimulating interleukin-6 and interleukin-8 production by lung fibroblasts.

Center of resistance of anterior arch segment

It is important to know the location of the center of resistance (CR) to control tooth movement. In this study, photoelastic techniques were used to determine the center of resistance. The photoelastic model included the anterior 4 maxillary teeth, which were interconnected firmly with 6 mm of space between lateral incisors and canines. Determination of the CR for the anterior arch segment was based on considerations of a wide variety of load conditions that generated the more uniform stresses in the supporting alveolar bone simulant. For the arch having the anterior 4 teeth connected, the CR was located within the mid-sagittal plane, 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor.

Imaging of the (1)H NMR second moment with (13)C chemical-shift resolution

A method of (13)C chemical-shift-resolved (1)H second moment imaging is proposed for molecular mobility imaging of heterogeneous materials. For evaluating the (1)H second moment, the method relies on the curve fitting procedure using spin-echo shapes indirectly: The information of (1)H echo shapes is transferred to the (13)C signal amplitude through (1)H-(13)C cross polarization and then the curve fitting is made using the (13)C signal amplitude. The (13)C signal is detected under (1)H dipolar decoupling and magic angle spinning, resulting in the incorporation of (13)C chemical-shift resolution. Imaging information is included in the (13)C signal by application of phase-encoding gradients. The second moment images obtained can reflect the molecular mobility at every molecular site separated by (13)C chemical shifts, yielding detailed information on the molecular mobility. The method is demonstrated by spatially 1D experiments performed on a model sample. Copyright 2000 Academic Press.

Initial and 6-month results of biodegradable poly-l-lactic acid coronary stents in humans

BACKGROUND

Although metallic stents are effective in preventing acute occlusion and reducing late restenosis after coronary angioplasty, many concerns still remain. Compared with metallic stents, poly-l-lactic acid (PLLA) stents are biodegradable and can deliver drugs locally. The aim of this study was to evaluate the feasibility, safety, and efficacy of the PLLA stent.

METHODS AND RESULTS

Fifteen patients electively underwent PLLA Igaki-Tamai stent implantation for coronary artery stenoses. The Igaki-Tamai stent is made of a PLLA monopolymer, has a thickness of 0.17 mm, and has a zigzag helical coil pattern. A balloon-expandable covered sheath system was used, and the stent expanded by itself to its original size with an adequate temperature. A total of 25 stents were successfully implanted in 19 lesions in 15 patients, and angiographic success was achieved in all procedures. No stent thrombosis and no major cardiac event occurred within 30 days. Coronary angiography and intravascular ultrasound were serially performed 1 day, 3 months, and 6 months after the procedure. Angiographically, both the restenosis rate and target lesion revascularization rate per lesion were 10.5%; the rates per patient were 6.7% at 6 months. Intravascular ultrasound findings revealed no significant stent recoil at 1 day, and they revealed stent expansion at follow-up. No major cardiac event, except for repeat angioplasty, developed within 6 months.

CONCLUSIONS

Our preliminary experience suggests that coronary PLLA biodegradable stents are feasible, safe, and effective in humans. Long-term follow-up with more patients will be required to validate the long-term efficacy of PLLA stents.

Protective effect of bisoprolol on beta-1 adrenoceptor peptide-induced autoimmune myocardial damage in rabbits

Idiopathic dilated cardiomyopathy is a severe disease of unknown etiology. Accumulating evidence suggests that agonist-like autoantibodies against the beta 1 adrenoceptor in the circulation of dilated cardiomyopathy may play an important role. The aim of this study was to evaluate the effects of the selective beta 1-adrenoceptor blocker, bisoprolol, on beta 1-adrenoceptor peptide induced autoimmune myocardial damage. In the animal model of autoimmune cardiomyopathy induced by active immunization of rabbits with beta 1-adrenoceptor peptide, bisoprolol was given at a dose of 3 mg/day throughout the study period. Our results showed high titer of anti-beta 1-adrenoceptor antibody in the immunized group throughout the study but not in the group receiving only bisoprolol. Cross-reactivity to beta 2 adrenoceptors was observed in some of the immunized rabbits, but disappeared almost entirely after 6 months. As compared to the beta 1-adrenoceptor peptide immunized group without bisoprolol treatment, bisoprolol treated beta 1-receptor peptide immunized group showed increase in the wall thickness and decreases in cavity dimension in anatomical measurements and only mild alterations in macro- and microscopic examinations. Thus, our study clearly demonstrated a beneficial effect of bisoprolol in rabbits who have developed autoimmune myocardial damage.

Low molecular weight dextran attenuates increase in extravascular lung water caused by ARDS

We studied the effect of low molecular weight dextran (mean molecular weight 40,000, Dextran 40; LMD) on the accumulation of extravascular lung water (EVLW), and also on hemodynamics and blood gases, in the oleic acid (OA)-injured lung in pentobarbital anesthetized rats. Starting just before the OA injection (0.01 mL/kg via femoral vein), 10% LMD in lactated Ringer's solution was infused throughout the experiment (5 mL/kg/h) instead of lactated Ringer's solution. OA caused acute lung injury leading to decreased oxygenation (PaO2: 87 +/- 11 mmHg versus control group 128 +/- 11) and an increased permeability of the alveolar-capillary membrane, as shown by increases in EVLW (4.89 +/- 0.54 versus control group 4.07 +/- 0.14), and albumin leakage (0.043 +/- 0.015 versus control group 0.010 +/- 0.004). LMD protected against the increase in EVLW (4.14 +/- 0.10) and the hypoxemia (112 +/- 19 mmHg), but it did not reduce the albumin leakage into the alveolar space (0.052 +/- 0.009). These data suggest that LMD may limit the fluid accumulation that is secondary to OA-induced lung injury.

[Rheumatoid arthritis-associated bronchiolitis successfully treated with erythromycin]

A 52-year-old man with a 4-year history of rheumatoid arthritis, and who had an episode of suspected BOOP in early 1994, was admitted to our hospital because of cough and fever. A chest X-ray film on admission showed small patchy infiltrates, and a computed tomographic (CT) scan showed centrilobular nodules and patchy infiltrates with thickened broncho-vascular bundles in both lungs. Transbronchial and thoracoscopic lung biopsies disclosed the coexistence of interstitial pneumonia with BOOP pattern, follicular bronchiolitis, and diffuse panbronchiolitis-like purulent and obliterative bronchiolitis. Due to findings of chronic sinusitis, the patient was treated with erythromycin for 8 weeks, and the abnormal CT shadows regressed. This was an interesting case of various pulmonary lesions associated with rheumatoid arthritis, and successfully treated with erythromycin.

Benign schwannoma of the esophagus removed by enucleation: report of a case

A submucosal tumor of the esophagus was enucleated by a thoracotomy. A microscopic examination showed the tumor to be composed of spindle-shaped cells showing mild nuclear atypia with vague nuclear palisading and scarce mitotic figures. The tumor was surrounded by peripheral lymphoid cuffs. An immunohistochemical study demonstrated diffuse positive staining for S-100 protein in the tumor cells. The lesion was diagnosed to be an esophageal schwannoma based on these pathological features. Benign schwannoma of the esophagus has been described in five cases in four reports in the English literature. This is the sixth case diagnosed by immunohistochemical studies.

Melleolides K, L and M, new melleolides from Armillariella mellea

Three new sesquiterpenoid aromatic esters designated melleolides K (1), L (2) and M (3) were isolated from the cultured mycelia of Armillariella mellea (Vahl. ex Fr.) Karst. Structures of these compounds were determined on the basis of various NMR spectral data, chemical transformations and X-ray analysis. Compounds 1, 2 and 3 showed antimicrobial activities.

A modification of Mayer's tannic acid-ferric chloride staining method for demonstrating cellular membranous systems for light microscopy

To observe cellular membranous systems under a light microscope, we modified Mayer's tannic acid-ferric chloride stain method by adding a treatment with hematoxylin after the original procedure. We used the modified tannic acid-ferric chloride (MTA-Fe) stain method to examine kidneys, liver, heart, trachea, epididymides and other organs of rats and dogs. The MTA-Fe stain clearly demonstrated the basement membrane, brush border, basolateral invaginations and cell processes in the kidneys which enabled easy differentiation of the S1 and S3 segments of proximal convoluted tubules. Our technique also demonstrated hepatic cell membranes and bile canaliculi in the liver, cross striations and longitudinal traveling of myofibrils in the heart, cilia of the epithelial cells in the trachea, and stereocilia and terminal bars in the epididymis. The MTA-Fe stain is a convenient method to visualize cellular membranous systems even for light microscopy. The stain has the advantages of using no toxic materials, simple and easy technique, little variation of staining results, and little fading for several months after staining.

Calcium channel antagonistic effects of AH-1058, a novel antiarrhythmic drug, on guinea-pig myocardium

Effects of AH-1058, a novel cyproheptadine derivative with high antiarrhythmic activity in in vivo arrhythmia models, were studied in guinea-pig myocardium. In coronary-perfused right ventricular tissue preparations, AH-1058 (10(-5) M) shortened the action potential duration with little effect on the resting membrane potential, maximum rate of rise and overshoot. AH-1058, 10(-7) M to 10(-5) M, concentration-dependently decreased the contractile force. The increase in contractile force by Ca2+ was markedly inhibited by 3 x 10(-6) M AH-1058 while that by isoproterenol was only slightly affected. In isolated ventricular myocytes, AH-1058 concentration-dependently decreased the nicardipine sensitive transient inward current with no effect on steady state currents, and decreased the amplitude of the evoked Ca2+ transient. These results suggest that AH-1058 has Ca2+ channel antagonistic effects which may contribute to its antiarrhythmic activity.

Enhanced expression of interleukin-6 in chronic hepatitis C

AIMS/BACKGROUND

There is a possibility that proinflammatory cytokines such as interleukin-6 (IL-6) are involved in the inflammatory process of chronic hepatitis C. This study was undertaken to investigate the possible role of IL-6 in the pathophysiology of chronic hepatitis C.

METHODS

Serum IL-6 levels in 63 patients with chronic hepatitis C and in 26 normal controls were measured. Light and electron immunostaining studies to localize IL-6 protein as well as in situ hybridization to localize IL-6 messenger RNA were performed on 10 liver biopsy specimens.

RESULTS

Serum IL-6 levels were significantly (p<0.01) elevated in chronic hepatitis C compared to those in normal controls. Although no statistically significant correlation was found between serum IL-6 levels and hepatobiliary enzyme levels, a significant correlation (p<0.01) was found between serum IL-6 levels and category II of Knodell's histological activity index score. Non-parenchymal cells in hepatic sinusoids and the cells infiltrating enlarged fibrous portal tracts were definitely positive for IL-6 protein and mRNA by immunohistochemistry and in situ hybridization. In addition, immunoelectron microscopy revealed a weak and occasional positive reaction in the cytoplasm of hepatocytes. The majority of the positive cells in hepatic sinusoids showed CD68 immunoreactivity in consecutive sections indicating that these were Kupffer cells. Sinusoidal endothelial cells and hepatic stellate cells also exhibited a weak reaction.

CONCLUSION

These results strongly suggest that Kupffer cells in liver parenchyma and macrophages infiltrating in portal tracts are the main producers of elevated IL-6 in serum. Moreover, there is a possibility that IL-6 produced by hepatocytes could also act as a regenerative stimulus to hepatocytes themselves in an autocrine fashion.

Design of clinical trials for recurrent events with periodic monitoring

This paper presents a design for randomized clinical trials in which incomplete data are collected on the occurrence of potentially recurrent events through periodic monitoring. In particular, events are assumed to arise according to a point process, but information is available at the times of monitoring only if one or more events has occurred since the preceding monitoring point. The event process is modelled via a piecewise Poisson process, and a proportional rates model is introduced to represent the difference in event rates between treatment groups. The design was developed on the basis of a Wald-type test derived from the generalized estimating equations of Liang and Zeger (Biometrika 73, 13-22 (1986)). Robustification of the variance of the estimator of the treatment effect was considered under a random effects model with a semi-parametric mixture distribution. The design was adopted to address issues which arose in an osteoporosis trial conducted in Japan.

Analysis of recurrent events: application to a clinical trial of colony stimulating factor with the endpoint of febrile neutropenia

This paper discusses the analysis of randomized clinical trials where the primary endpoint is a recurrent event observed during a time period which can vary among patients. In particular it describes a method of estimating robust confidence limits for clinically relevant parameters. As an illustrative example, a clinical trial of a macrophage colony stimulating factor (M-CSF) for patients with acute myeloblastic leukaemia (AML) is introduced where the endpoint is the incidence and duration of febrile neutropenia. The causal effects in the framework of Rubin's deterministic model are defined as estimands. A non-parametric method based on the permutation test, using an accelerated search procedure proposed by Garthwaite, is compared with other standard methods by simulation and by application to the AML trial data.

Herbimycin A inhibits both dephosphorylation and translocation of cofilin induced by opsonized zymosan in macrophagelike U937 cells

We previously reported that a 21-kDa phosphoprotein may play an important role in superoxide production through dephosphorylation by neutrophillike differentiated HL-60 cells (Suzuki et al., 1995, Biochim Biophys Acta 1266: 261-267). The phosphoprotein was identified as cofilin, an actin-binding protein, and the activation-induced changes in its intracellular distribution have been described elsewhere (Suzuki et al., 1995, J Biol Chem 270:19551-19556). However, the physiologic roles of cofilin in phagocytes remain to be established, and the regulatory mechanisms for dephosphorylation and translocation of cofilin are unknown. In the present study, we investigated the roles of cofilin in the opsonized zymosan (OZ)-activated macrophagelike U937 cells by using herbimycin A, an inhibitor for protein tyrosine kinase. In the individual adherent phagocytes, OZ induced many events: 1) production of superoxide, 2) phagocytosis of the insoluble particles OZ, 3) dephosphorylation of cofilin, 4) translocation of cofilin from cytosol to plasma membrane regions, 5) decrease in intracellular pH from 7.4 to aprroximately 6.8, and 6) rapid and transient increase in filamentous actin at the cell periphery. All of these events were inhibited or reduced significantly by herbimycin A. OZ increased phosphorylation of tyrosine in 110-, 50-, 34-, and 29-kDa proteins, whereas herbimycin A inhibited it. These results suggest that tyrosine kinase plays an essential role upstream of these events through phosphorylation of such proteins. Furthermore, microinjection of anti-cofilin antibody to the differentiated U937 cells caused inhibition of the phagocytosis. These results suggest that cofilin plays critical roles in phagocytic functions through changes in cytoskeletal organization.

Role of the endogenous prostaglandin E2 in human lung fibroblast interleukin-11 production

Interleukin-11 (IL-11) is known to be a member of the interleukin-6 (IL-6)-type cytokine family. IL-11 is likely to be a major determinant of immune regulation in acute and chronic inflammatory lung diseases, although it is not directly linked with specific disease processes. It has already been shown that although unstimulated human lung fibroblasts did not produce significant amounts of IL-11, the addition of interleukin-1 alpha (IL-1 alpha) and/or transforming growth factor-beta (TGF-beta) stimulated fibroblasts dose-dependently to produce IL-11. Northern blot analysis showed that these stimulators also upregulated IL-11 mRNA expression. As it has been previously reported that IL-1 and TGF-beta stimulate prostaglandin E2 (PGE2) release from lung fibroblasts, we investigate here the role of endogenous PGE2 and the direct effects of the two inhibitors of prostaglandin synthesis, indomethacin and dexamethasone, on IL-11 production by human lung fibroblasts. The addition of indomethacin, a cyclo-oxygenase inhibitor, resulted in significant suppression of IL-11 production and mRNA expression in lung fibroblasts. There was no detectable effect of PGE2 alone on IL-11 levels; however, the suppression of IL-11 production by indomethacin was almost completely reversed by addition of PGE2. In contrast, suppression of IL-11 production by indomenthacin was not reversed by addition of thromboxane B2 and carbocyclic thromboxane A2. In addition, dexamethasone completely suppressed IL-11 production and downregulated IL-11 mRNA. These results suggest that endogenous PGE2 acts as an autocrine stimulus for IL-11 production by human lung fibroblasts activated by IL-1 alpha and TGF-beta.

Active immunization of combined beta1-adrenoceptor and M2-muscarinic receptor peptides induces cardiac hypertrophy in rabbits

BACKGROUND

The high prevalence of patients with dilated cardiomyopathy (DCM) with anti-beta1-adrenoceptor and/or anti-M2-muscarinic receptor autoantibodies in their sera has been observed. However, the pathophysiological role of these autoantibodies in the development of cardiomyopathy is unknown. We previously reported an experimental model of early-stage DCM-like cardiomyopathy induced by immunizing rabbits for 1 year with synthetic peptides corresponding to the sequence of the second extracellular loop of either beta1-adrenoceptor or M2-muscarinic receptor. Because approximately half the sera of patients with DCM that recognize one of the two receptor sequences also recognize the second sequence, a model was created in rabbits simultaneously immunized with the synthetic peptides corresponding to the second extracellular loop of the beta1-adrenoceptor and M2-muscarinic receptor.

METHODS AND RESULTS

All rabbits (n = 8) immunized with both peptides had a high titer of both anti-beta1-adrenoceptor and anti-M2-muscarinic receptor autoantibodies in their sera, whereas none of the sera from control rabbits injected with saline (n = 9) was positive. No significant cross-reaction with peptides other than those used for immunization was found. The weight of the hearts of immunized rabbits increased significantly. The hearts of immunized rabbits showed marked concentric left ventricular hypertrophy with mild inflammatory cell infiltration. In these rabbits, mild or moderate interstitial fibrosis was also observed. In electron micrographs, immunized rabbits showed focal myofibrillar lysis, loss of myofilament, and a marked increase in the number of mitochondria and deposition of dense granules in both sarcoplasm and myofibrils. Conversely, one of the control rabbits showed scant mononuclear cell infiltration. However, in this control rabbit, no significant alteration was found by electron microscopy.

CONCLUSION

Our results showed the coexistence of both anti-beta1-adrenoceptor and anti-M2-muscarinic receptor autoantibodies in the sera has pathophysiological importance, shown by their ability to induce cardiac hypertrophy in rabbits.

A human homolog of Drosophila lethal(3)malignant brain tumor (l(3)mbt) protein associates with condensed mitotic chromosomes

The lethal(3)malignant brain tumor (D-l(3)mbt) gene is considered to be one of the tumor suppressor genes of Drosophila, and its recessive mutations are associated with malignant transformation of the neuroblasts in the larval brain. The structure of D-l(3)mbt protein is similar to Drosophila sex comb on midleg (Scm) protein which is a member of Polycomb group (PcG) proteins. We have isolated here the first human homolog of the D-l(3)mbt gene, designated h-l(3)mbt. Radiation hybrid mapping and fluorescence in situ hybridization (FISH) analysis localized the h-l(3)mbt gene to chromosome 20q12. The h-l(3)mbt transcript is expressed in most of the human adult normal tissues and cultured cell lines. However, some cancer cells markedly reduce the h-l(3)mbt protein expression. Immunocytochemical study revealed that the h-l(3)mbt protein shows a speckled and scattered distribution in interphase nuclei and completely associates with condensed chromosomes in mitotic cells. This subcellular localization has been shown to be different from that of Bmi1 protein which is a component of PcG complex. Furthermore, overexpression of h-l(3)mbt protein by using a Cre-mediated gene activation system leads to failures of proper chromosome segregation and cytokinesis, which result in formation of multinuclei in U251MG cells. These observations suggest that h-l(3)mbt protein has functions distinct from those of PcG proteins and may play a role in proper progression of cell division.

A model for CD8+ CTL tumor immunosurveillance and regulation of tumor escape by CD4 T cells through an effect on quality of CTL

Understanding immune mechanisms influencing cancer regression, recurrence, and metastasis may be critical to developing effective immunotherapy. Using a tumor expressing HIV gp160 as a model viral tumor Ag, we found a growth-regression-recurrence pattern, and used this to investigate mechanisms of immunosurveillance. Regression was dependent on CD8 T cells, and recurrent tumors were resistant to CTL, had substantially reduced expression of epitope mRNA, but retained the gp160 gene, MHC, and processing apparatus. Increasing CTL numbers by advance priming with vaccinia virus expressing gp160 prevented only the initial tumor growth but not the later appearance of escape variants. Unexpectedly, CD4 cell depletion protected mice from tumor recurrence, whereas IL-4 knockout mice, deficient in Th2 cells, did not show this protection, and IFN-gamma knockout mice were more susceptible. Purified CD8 T cells from CD4-depleted mice following tumor regression had more IFN-gamma mRNA and lysed tumor cells without stimulation ex vivo, in contrast to CD4-intact mice. Thus, the quality as well as quantity of CD8+ CTL determines the completeness of immunosurveillance and is controlled by CD4 T cells but not solely Th2 cytokines. This model of immunosurveillance may indicate ways to enhance the efficacy of surveillance and improve immunotherapy.

Characterisation of a synergistic interaction between a thymidylate synthase inhibitor, ZD1694, and a novel lipophilic topoisomerase I inhibitor karenitecin, BNP1100: mechanisms and clinical implications

We developed a combination protocol for inhibitors of thymidylate synthase (TS) and DNA topoisomerase I (Topo I) that can exert highly lethal effects in vitro against HCT-8 human colorectal cancer cells. The specific schedule was constructed so that a TS inhibitor could induce not only primary DNA damage but also cellular conditions optimal for the efficient action of a Topo I inhibitor. The initial drug treatment consisted of a brief exposure to a quinazoline-based antifolate, ZD1694. After an interval of approximately one cell-doubling time, cells were exposed for 8-24 h to BNP1100, a Karenitecin-class 7-thiomethyl-camptothecin, in the presence of 1-10 microM thymidine; the latter acted as a crucial factor to promote the collision of moving replication forks with the drug-stabilised DNA-Topo I cleavable complexes even under continuous TS inhibition. Clonogenic analyses confirmed that these mechanistically distinct drugs at clinically achievable concentrations worked in a highly synergistic manner, with a maximum effect abolishing the viability of virtually all cancer cells (> 99.9%). The pretreatment with ZD1694 increased the amount of DNA-bound Topo I by up to 4-fold and the DNA-damaging capability of BNP1100 by up to 15-fold. The possibility of at least four DNA-damaging pathways is proposed which might have resulted from the individual actions of TS and Topo I inhibitors as well as their concerted actions. Taken together, the present findings provided a logically permissible explanation as to why TS and Topo I inhibitors in concerted interactions induced a highly lethal effect which was more than a simple additive effect. Since these drugs are effective specifically on actively proliferating cancer cells, but not on non-cycling G0/G1 cells, this mechanism-based protocol may warrant consideration for clinical verification.

Syndrome of inappropriate secretion of antidiuretic hormone associated with amyotrophic lateral sclerosis in respiratory failure

A 65-year-old man who had muscle weakness and dysarthria was admitted for investigation of motor neuron disease. He had lost 12 kg of weight in 6 months. Neurological findings disclosed upper and lower motor neuron disturbances with normal sensory nerve function, and needle electromyography showed a neurogenic pattern. Laboratory findings on admission demonstrated dilutional hyponatraemia due to an excessive secretion of antidiuretic hormone (ADH). Based on these findings, the patient was diagnosed as having the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) associated with amyotrophic lateral sclerosis (ALS). During the night of first hospital day, the patient complained of severe dyspnoea, and mechanical ventilation was commenced. Following the mechanical ventilation, plasma ADH levels and serum sodium concentration were normalized. We propose that respiratory failure secondary to the atrophy of respiratory muscle might be responsible for the development of SIADH.

Reactive oxygen intermediates stimulate interleukin-6 production in human bronchial epithelial cells

Reactive oxygen intermediates (ROIs) play an important role in the initiation and progression of lung diseases. In this study, we investigated whether ROIs were involved in the induction of interleukin (IL)-6 in human bronchial epithelial cells. We exposed normal human bronchial epithelial cells as well as a human bronchial epithelial cell line, HS-24, to ROIs. We measured the amount of IL-6 in the culture supernatants using ELISA and the IL-6 mRNA levels using RT-PCR. Superoxide anions (O-2), but not hydrogen peroxide (H2O2), increased IL-6 production. To examine whether it is a cell type-specific mechanism of airway epithelial cells, the experiments were also performed in human lung fibroblasts, WI-38-40. In WI-38-40 cells, neither O-2 nor H2O2 increased IL-6 production. In contrast, tumor necrosis factor (TNF)-alpha (200 U/ml) induced IL-6 at the protein and mRNA levels in both airway epithelial cells and lung fibroblasts. This cytokine-induced IL-6 production was significantly suppressed by several antioxidants, including dimethyl sulfoxide (DMSO), in airway epithelial cells. In WI-38-40 cells, DMSO was not able to suppress IL-6 production induced by TNF-alpha. Pretreatment with DMSO recovered the TNF-alpha-induced depletion of intracellular reduced glutathione in HS-24 cells. These findings indicate that oxidant stress specifically induces IL-6 production in human bronchial epithelial cells and that in these cells ROIs may be involved in IL-6 production after stimulation with cytokines such as TNF-alpha. Presumably, ROIs participate in the local immune response in lung diseases via IL-6 release from bronchial epithelial cells.

Magic echo solid-state NMR imaging without a rapidly switchable field gradient

To relax the high-speed requirement imposed on the gradient system used in solid-state proton imaging, we propose two simple modifications of the magic echo imaging sequence, TREV-16TS. In the first modification, the applied gradient is inverted in the middle of the RF irradiation; the second modification utilizes a sinusoidal gradient synchronized with the RF sequence. It is estimated by experiments that as long as the RF amplitude is at least about 10 times stronger than the resonance offset induced by the gradient, the spatial resolution is not degraded significantly by the line narrowing deterioration due to the gradient applied during the on-resonance RF irradiation. The modifications allow commercially available standard gradients to be used for the magic echo imaging of solids. Copyright 1999 Academic Press.

Autoantibodies against M2 muscarinic receptors in patients with cardiomyopathy display non-desensitized agonist-like effects

Circulating autoantibodies against the human M2 muscarinic receptors have been previously shown in 38% of patients with idiopathic dilated cardiomyopathy. The functional properties of these autoantibodies are reported herein. They were able to decrease the cell beating frequency of myocytes in cultured neonatal rat heart cells in a dose-dependent manner without desensitization over a period of more than 5 hours whereas the non-specific muscarinic receptor agonist carbachol also inhibited the heart cell beating frequency but was desensitized within 1 hour. In the same cell culture, anti-M2 muscarinic receptor autoantibodies were not able to induce internalization of muscarinic receptor whereas carbachol did. These results demonstrate for the first time that anti-M2 muscarinic receptor autoantibodies from patients with idiopathic dilated cardiomyopathy have stimulatory muscarinic activity in vitro, which differ from normal muscarinic agonists by non-desensitization.

Effective utilization of N2-ethyl-2'-deoxyguanosine triphosphate during DNA synthesis catalyzed by mammalian replicative DNA polymerases

Acetaldehyde is produced by metabolic oxidation of ethanol after drinking alcoholic beverages. This agent reacts with nucleosides and nucleotides, resulting in the formation of N2-ethyl-guanine residues. N2-ethyl-2'-deoxyguanosine (N2-ethyl-dG) adduct has been detected in the lymphocyte DNA of alcoholic patients [Fang, J. L., and Vaca, C. E. (1997) Carcinogenesis 18, 627-632]. Thus, the nucleotide pool is also expected to be modified by acetaldehyde. N2-Ethyl-2'-deoxyguanosine triphosphate (N2-ethyl-dGTP) was chemically synthesized. The utilization of N2-ethyl-dGTP during DNA synthesis was determined by steady-state kinetic studies. N2-Ethyl-dGTP was efficiently incorporated opposite template dC in reactions catalyzed by mammalian DNA polymerase alpha and delta. When pol alpha was used, the insertion frequency of N2-ethyl-dGTP was 400 times less than that of dGTP, but 320 times higher than that of 7,8-dihydro-8-oxo-2'-deoxyguanosine triphosphate (8-oxo-dGTP), an oxidative damaged nucleotide. Using pol delta, the insertion frequency of N2-ethyl-dGTP was only 37 times less than that of dGTP. The chain extension from dC:N2-ethyl-dG pair occurred much more rapidly: the extension frequencies for pol alpha and pol delta were only 3.8 times and 6.3 times, respectively, lower than that of dC:dG pair. We also found that N2-ethyl-dG can be detected in urine samples obtained from healthy volunteers who had abstained from drinking alcohol for 1 week before urine collection. This indicates that humans are exposed constantly to acetaldehyde even without drinking alcoholic beverages. Incorporation of N2-ethyl-dG adducts into DNA may cause mutations and may be related to the development of alcohol- and acetaldehyde-induced human cancers.

Initial and long-term results of angioplasty in unprotected left main coronary artery

Angioplasty of the unprotected left main coronary artery (LMCA) has been controversial. Although recent single-center studies suggest that new devices may change the situation, many questions and problems remain. Therefore, the results of unprotected left main coronary angioplasty of 175 procedures in 107 patients were analyzed to evaluate its feasibility and effectiveness. The treatment of the initial 107 cases included balloon angioplasty (39 cases, 36%), directional coronary atherectomy (53 cases, 50%), and stents (15 cases, 14%). They were divided into 3 major subgroups: (1) acute group (n = 14), in which LMCA angioplasty was performed in patients with acute myocardial infarction; (2) emergency group (n = 10); and (3) elective group (n = 83). In-hospital mortality was higher in the acute (35.7%) and emergency (40.0%) groups than in the elective group (3.6%; p <0.0001). Angiographic follow-up was routinely performed and the restenosis rate including in-hospital restenosis was 70% in the acute group, 37.5% in the emergency group, and 40% in the elective group (p = NS). The mean clinical follow-up period was 2.9 years, and the estimated 5-year survival rates of the acute and emergency groups were 50% and 48.2%, respectively. However the 5-year survival rate of the elective group was higher than that seen in the acute or emergency group (77.5%; p <0.05). Repeat LMCA angioplasty was performed in 37 of 68 patients with 8.8% mortality (38.5% of acute and emergency cases and 1.8% of elective cases). The results indicated that elective unprotected LMCA angioplasty is relatively feasible and effective under scheduled angiographic follow-up.

Expression of E-cadherin and alpha-catenin in patients with colorectal carcinoma. Correlation with cancer invasion and metastasis

Cadherins form complexes with groups of cytoplasmic proteins, such as alpha-, beta-, and gamma-catenins, that link the cadherin molecule to the cytoskeleton. In this study, we conducted an immunohistochemical investigation of E-cadherin and alpha-catenin expression in 100 tissue samples obtained from colorectal cancer patients undergoing surgical treatment. Reduced expression of alpha-catenin was observed in 56 (56%) of the cases and found to be significantly correlated with the depth of invasion of the patients' colorectal cancer and its metastasis to lymph nodes and liver. In contrast, E-cadherin expression was reduced in 29 (29%) of the cases and was not significantly correlated with either depth of invasion or metastasis. Although the levels of expression of these proteins were positively correlated, coexpression pattern analysis showed that invasion and metastasis were correlated with a reduction of alpha-catenin expression regardless of the status of E-cadherin staining. Thus, to predict tumor invasion and metastasis in colorectal adenocarcinoma, it is useful to investigate not just the expression of E-cadherin but also the expression of alpha-catenin.

Mutagenic specificity of a derivative of 3-nitrobenzanthrone in the supF shuttle vector plasmids

3-Nitrobenzanthrone (NBA) is a powerful bacterial mutagen and a suspected human carcinogen present in diesel exhaust and airborne particulates [Enya, T., et al. (1997) Environ. Sci. Technol. 31, 2772-2776]. In the accompanying paper [Enya, T., et al. (1998) Chem. Res. Toxcol. 11, 1460-1467], N-acetoxy-N-acetyl-3-aminobenzanthrone (N-Aco-N-Ac-ABA) was synthesized to yield the DNA adducts of NBA. In this work, to investigate the mutagenic specificity of NBA in human cells, we analyzed mutations induced by N-Aco-N-Ac-ABA using the supF shuttle vector plasmids. Base sequence analysis of 110 and 100 plasmids with mutations in the supF gene propagated in normal cells [WI38-VA13] and nucleotide excision repair deficient cells [XP2OS(SV)], respectively, revealed that the majority of the mutations were base substitutions (85 and 90%) and the rest were deletions and insertions (10 and 15%) in both cell lines. About half of the mutant plasmids had a single base substitution. Of the base substitutions, the most frequent mutation was G.C to T.A transversion (41 and 51%), followed by G.C to A.T transitions (18 and 24%) in either cell. The mutations were distributed not randomly but located at several hot spots, and almost all (nine of ten) hot spots were at the sites of G.C base pairs. The polymerase stop assay in the supF gene revealed that N-Aco-N-Ac-ABA preferentially bound to guanine residues, and mutation sites were generally consistent with the sites where the guanine adducts were formed.

Bradykinin stimulates interleukin-8 production by human lung fibroblasts

Bradykinin (BK) is a potent inflammatory mediator that is generated from kininogens by the actions of plasma and tissue kallikreins. Lung fibroblasts have the potential to participate in the inflammatory responses by releasing proinflammatory cytokines in response to a variety of stimuli. We postulated that human lung fibroblasts might produce interleukin-8 (IL-8) in response to BK stimulation. The present study showed that BK stimulated human lung fibroblasts to produce IL-8 in a dose- and time-dependent manner. Furthermore, Northern blot analysis showed that BK increased IL-8 mRNA expression. The stimulatory effect of BK on IL-8 production was detected at the concentration of 10 nm, and the maximal stimulation was achieved with 100 to 1000 nm. Phorbol 12-myristate 13-acetate pretreatment diminished the ability of BK to stimulate IL-8 production. In addition, GF109203X, a selective protein kinase C inhibitor, blocked BK-induced IL-8 production. These observations suggest that the stimulatory effect of BK on IL-8 production by lung fibroblasts is, at least partially, mediated through protein kinase C. These data suggest that BK may be involved in the inflammatory reaction leading to interstitial lung disorders through stimulating IL-8 production by lung fibroblasts.

An unusual DNA adduct derived from the powerfully mutagenic environmental contaminant 3-nitrobenzanthrone

The covalent binding of an N-hydroxy metabolite of the powerfully mutagenic 3-nitrobenzanthrone (NBA) to 2'-deoxyguanosine (dG) and calf thymus DNA has been investigated in vitro. The major adduct obtained from the reaction of the N-acetoxy-N-acetyl derivative (N-Aco-N-Ac-ABA) of 3-aminobenzanthrone (ABA) and dG was identified as N-acetyl-3-amino-2-(2'-deoxyguanosin-8-yl)benzanthrone (dG-N-Ac-ABA) by 1H NMR and mass spectroscopies as well as by the reaction of N-Aco-N-Ac-ABA with the double-stranded calf thymus DNA. The coupling with the dG moiety occurred exclusively at C-2 of benzanthrone (BA), suggesting a significant contribution of a resonance-stabilized arenium ion intermediate derived from BA to the production of this new type of adduct. The preferred conformation of the adduct has been shown to be syn by 1H and 13C NMR.

Long-term effects of delapril hydrochloride on procollagen type III amino-terminal peptide, left ventricular mass and left ventricular function in hypertensive patients

The long-term effect of delapril hydrochloride, a non-sulfhydryl angiotensin converting enzyme inhibitor, on serum concentrations of procollagen type III amino-terminal peptide (PIIIP) and left ventricular mass (LVM) and function were investigated in 15 hypertensive patients. Patients were treated with delapril hydrochloride 30 mg/day po for 12 months. Blood samples and an echocardiogram were obtained before treatment and after 6 and 12 months of treatment. Blood pressure, PIIIP, and LVM significantly decreased associated with an increase in left ventricular fractional shortening and mean systolic and diastolic posterior wall velocity at 6 and 12 months of treatment. Positive correlations between PIIIP and LVM (r=0.49, p<0.005) and negative correlations between PIIIP and left ventricular fractional shortening (r=-0.31, p<0.05) were found. Delapril hydrochloride reduced PIIIP and LVM and improved cardiac function in hypertensive patients.

Molecular analysis of mutations induced by acrolein in human fibroblast cells using supF shuttle vector plasmids

Types of mutations induced by acrolein in the supF gene on the shuttle vector plasmid pMY189 replicated in normal human fibroblast cells were examined. Base sequence analysis of 92 plasmids with mutations in the supF gene revealed that the majority of the mutations were base substitutions (76%) and the others were deletions and insertions (24%). Single base substitutions were most frequently found (46%), while multiple base substitutions were 18% and tandem (two adjacent) base substitutions were 12% of the mutations. Of the base substitution mutations, G:C to T:A transversions were 44% and G:C to A:T transitions were 24%. The mutations were distributed not randomly but located at several hotspots. Acrolein produced DNA intra-strand cross-links between guanine residues, which might be responsible for rather high induction of the tandem base substitution mutations.

Topoisomerase-I inhibitor SN-38 can induce DNA damage and chromosomal aberrations independent from DNA synthesis

BACKGROUND

SN-38 is the active metabolite of the topoisomerase-I (topo-I) inhibitor Irinotecan (CPT-11). Generally, topo-I inhibitors stabilize the complex between topo-I and DNA which collide with moving DNA replication forks, eventually leading to double stranded DNA damage. Therefore, topo-I inhibitors are regarded as S-phase specific. The present study investigated S-phase dependent and independent effects of SN-38.

MATERIALS AND METHODS

Effects of exposure of A2780 cells to SN-38 (2 hours) were studied by assessing DNA/protein crosslinks, DNA damage and cytogenetic aberrations.

RESULTS

A close correlation (r2 = 0.97) was established between drug-induced DNA/protein crosslinks and double stranded DNA breaks. Cytogenetic analysis revealed near maximum clastogenic effects already evident immediately following 2 hours drug exposure. However, qualitatively, chromatid breaks at 24 hours were different from those at 0 hours, in that at 24 hours they were associated with radial chromosome configurations and sister chromatid exchanges.

CONCLUSION

The data corroborate that the S-phase dependent mechanism of action of topo-I inhibitors is also applicable to SN-38. The cytogenetic data indicate two distinct interactions of SN-38 with DNA: immediate induction of chromatid breaks independent from DNA synthesis, and induction of chromatid breaks associated with radial chromosome configurations dependent on DNA synthesis.

Cross polarization for 1H NMR image contrast in solids

A novel 1H imaging method for solids, yielding images reflecting 1H-13C dipolar interactions through cross relaxation time TIS, is presented. Phase-alternating multiple-contact cross polarization (PAMC CP) was incorporated into the magic-echo frequency-encoding imaging scheme; the PAMC CP sequence may partly but efficiently destroy the initial 1H magnetization depending on the TIS values. A theory describing the effects of the PAMC CP sequence was developed, which was used for the assessment of the sequence as well as the analysis for the experimental results. It was demonstrated that the TIS-weighted 1H image and the TIS mapping for a phantom, constituted of adamantane and ferrocene, can distinguish these compounds clearly. Copyright 1998 Academic Press.

Population-based prevalence of symptomatic and asymptomatic astrovirus infection in rural Mayan infants

Symptomatic and asymptomatic astrovirus infection was prospectively determined in a 3-year birth cohort of Mayan infants. Stool samples from 271 infants and 268 older siblings were tested for astrovirus, adenovirus 40/41, rotavirus and Salmonella, Shigella and Campylobacter species. Concurrent diarrhea, vomiting, fever, or anorexia were noted. Astrovirus was detected in 164 infants (61%) and 20 siblings (7%). Rotavirus (4%) and adenovirus 40/41 (13%) were isolated less frequently. Of all diarrheal episodes reported at a visit, 26% (78/305) were associated with astrovirus; 17% (78/452) of astrovirus infections were associated with diarrhea and 9% with other symptoms. Only diarrhea was associated with astrovirus infection (odds ratio, 1.4; 95% confidence interval [CI], 1.07-1.92; P = .01). Of infants with astrovirus, 70% shed at multiple visits over a period of 2-17 weeks (median, 5). The point prevalence of astrovirus infection was significantly higher among infants than siblings (relative risk, 6.18; 95% CI, 3.93-9.72; P < .0001, chi2). Astrovirus was identified throughout the year, peaked in March and May, and decreased in September. In this population, astrovirus was the most common enteric pathogen isolated; symptomatic infection was prevalent among infants.

Functional evaluation using motor scores after cervical spinal cord injuries

Patient evaluation using Zancolli's classification for cervical cord injuries uses easily understood criteria and accurately defines the state of disability in Frankel grade A or B patients. However, this classification cannot be used in Frankel grade C patients even though they also cannot walk. We compared the Zancolli classification with American Spinal Injury Association (ASIA) motor scores in evaluating self-care in Frankel grade C patients. The Zancoli classification was found to correlate closely with the ASIA motor score. The threshold of ability to perform self-care in areas such as urinary toileting and wheelchair mobility occurred approximately between C6A and C6B 1 in the Zancolli classification in Frankel grade A and B patients and at the level of about 30 points in the ASIA motor score in Frankel grade C patients. The ASIA motor score is helpful in defining functional motor status in Frankel grade C patients with cervical spinal cord injuries.

[Chronic necrotizing pulmonary aspergillosis resistant to antimycotic drugs and treated by partial pulmonary resection]

A 46-year-old man with a history of left upper lobectomy for pulmonary tuberculosis was admitted to our hospital because of dilated cardiomyopathy. During hospitalization, fever and weight loss developed. The cause was suspected to be a round mass inside a cavity and a neighboring infiltrative shadow in the left upper lung field as seen on chest radiography. A percutaneous needle biopsy was done, and examination of the specimen showed an aggregate of Aspergillus fumigatus hyphae. Fluconazole (FCZ) was injected through an intracavitary catheter every day, and was then given by mouth. Treatment with FCZ was effective temporarily. However, he was again admitted to our hospital because of lower extension of the cavity and deteriorated inflammatory findings. From the clinical course, chronic necrotizing pulmonary aspergillosis was diagnosed. Treatment with all available antifungal agents did not improve his condition. Although he had decreased cardiac function due to dilated cardiomyopathy, partial pulmonary resection was done. The cavity with the fungus ball was resected completely. As of the time of this writing, he remains free of aspergillosis.

[Analysis of 18 breast cancer patients with hypercalcemia]

A total of 91 breast cancer patients died of advanced and recurrent breast cancer at the Osaka Teishin Hospital from 1986 to 1996. There were 18 cases (19.8%) among them showing hypercalcemia (serum corrected Ca > or = 11.0 mg/dl). These 18 cases were analyzed to determine the incidence of hypercalcemia and to find a more effective treatment. All these patients had multiple bone metastases during their clinical course, and six patients (33.3%) had pathologic bone fracture just before the occurrence of hypercalcemia. Their common symptoms were general fatigue, gastrointestinal symptoms, renal dysfunction or neurological symptoms. There was no definitive correlation between clinical signs and serum calcium values. Among various therapies, the use of pamidronate disodium (Aredia) in combination with hydration, steroid and calcitonin was found to be the most effective treatment for hypercalcemia. The survival time from the diagnosis of hypercalcemia in the patients undergoing treatment with Aredia was significantly better than without it (p < 0.01). This suggests that Aredia should be effective and useful for advanced breast cancer patients with hypercalcemia.

Myocardial injury due to G-protein coupled receptor-autoimmunity

One of the main mechanisms for dilated cardiomyopathy is likely to be autoimmune mediated myocardial damage. So far, a variety of autoantibodies have been detected against a number of putative autoantigens in the sera of patients with dilated cardiomyopathy. A growing body of studies have confirmed that autoantibodies against the second extracellular loop of beta 1-adrenoceptors and M2-muscarinic receptor are present in 30-40% of patients with dilated cardiomyopathy. These anti-beta 1-adrenoceptor and anti-M2-muscarinic receptor antibodies can not only decrease the binding sites of antagonist but also recognize the target receptors. Moreover, these two autoantibodies possess an 'agonist-like' stimulatory effect on the target receptors. In order to elucidate whether the autoantibodies against these autoimmune epitopes play an important role in the pathogenesis of dilated cardiomyopathy, we immunized rabbits over a period of one year with synthetic peptides corresponding to the second extracellular loop of the beta 1-adrenoceptor and the M2-muscarinic receptor. These peptides induced morphological changes in the heart similar to those found in dilated cardiomyopathy. These clinical and experimental findings suggest that these receptor autoantigens are of pathogenic importance in the development of dilated cardiomyopathy in vivo.

Specific tandem GG to TT base substitutions induced by acetaldehyde are due to intra-strand crosslinks between adjacent guanine bases

Acetaldehyde is present in tobacco smoke and automotive exhaust gases, is produced by the oxidation of ethanol, and causes respiratory organ cancers in animals. We show both the types and spectra of acetaldehyde-induced mutations in supF genes in double- and single-stranded shuttle vector plasmids replicated in human cells. Of the 101 mutants obtained from the double-stranded plasmids, 63% had tandem base substitutions, of which the predominant type is GG to TT transversions. Of the 44 mutants obtained from the single-stranded plasmids, 39% had tandem mutations that are of a different type than the double-stranded ones. The GG to TT tandem substitutions could arise from intra-strand crosslinks. Our data indicate that acetaldehyde forms intra- as well as inter-strand crosslinks between adjacent two-guanine bases. Based upon the following observations: XP-A protein binds to acetaldehyde-treated DNA, DNA excision repair-deficient xeroderma pigmentosum (XP) cells were more sensitive to acetaldehyde than the repair-proficient normal cells, and a higher frequency of acetaldehyde-induced mutations of the shuttle vectors was found in XP cells than in normal cells, we propose that the DNA damage caused by acetaldehyde is removed by the nucleotide excision repair pathway. Since treatment with acetaldehyde yields very specific GG to TT tandem base substitutions in DNA, such changes can be used as a probe to identify acetaldehyde as the causal agent in human tumors.